(A) study of thin film encapsulation barrier for wearable organic electronics

Abstract

When we think about clothes, they are usually formed with textiles and have to be both wearable and washable for daily use

however, wearable electronics has had a problem with its power sources and moisture permeability, which causes the devices to malfunction. To ease out the problem of external power sources and enhance the practicability of wearable displays, the author fabricated wearing display modules on real textiles that integrated polymer solar cells (PSCs) with organic light emitting diodes (OLEDs).

PSCs have been one of the most promising candidates for a next-generation power source, especially for wearable and optoelectronic applications because they can provide stable power without an external power source, while OLEDs can be driven with milliwatts. However, the problem was that they are both very vulnerable to external moisture and oxygen. The encapsulation barrier is essential for their reliability. The conventional encapsulation barrier is sufficient for normal environments

however, it loses its characteristics in aqueous environments, such as water. It limits the commercialization of wearing displays that must operate even on rainy days or after washing.

To tackle this issue, the author employed a washable encapsulation barrier that can protect the device without losing its characteristics after washing through atomic layer deposition (ALD) and spin coating. With this encapsulation technology, the author confirmed that textile-based wearing display modules including PSCs, OLEDs, and the proposed encapsulation barrier exhibited little change in characteristics even after 20 washings with 10-minute cycles. Moreover, the encapsulated device operated stably with a low curvature radius of 3mm and boasted high reliability.

Finally, it exhibited no deterioration in properties over 30 days even after being subjected to both bending stress and washing. Since it uses a less stressful textile, compared to conventional wearable electronic devices that use traditional plastic substrates, this technology can accelerate the commercialization of wearing electronic devices. Importantly, this wearable electronic device in daily life can save energy through a self-powered system.